/*
 * Copyright (c) 1995, 2004, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package java.lang;

/**
 * Thrown when an application tries to load in a class through its
 * string name using:
 * <ul>
 * <li>The <code>forName</code> method in class <code>Class</code>.
 * <li>The <code>findSystemClass</code> method in class
 * <code>ClassLoader</code> .
 * <li>The <code>loadClass</code> method in class <code>ClassLoader</code>.
 * </ul>
 * <p>
 * but no definition for the class with the specified name could be found.
 *
 * <p>As of release 1.4, this exception has been retrofitted to conform to
 * the general purpose exception-chaining mechanism.  The "optional exception
 * that was raised while loading the class" that may be provided at
 * construction time and accessed via the {@link #getException()} method is
 * now known as the <i>cause</i>, and may be accessed via the {@link
 * Throwable#getCause()} method, as well as the aforementioned "legacy method."
 *
 * @author unascribed
 * @see java.lang.Class#forName(java.lang.String)
 * @see java.lang.ClassLoader#findSystemClass(java.lang.String)
 * @see java.lang.ClassLoader#loadClass(java.lang.String, boolean)
 * @since JDK1.0
 */
public class ClassNotFoundException extends ReflectiveOperationException {

  /**
   * use serialVersionUID from JDK 1.1.X for interoperability
   */
  private static final long serialVersionUID = 9176873029745254542L;

  /**
   * This field holds the exception ex if the
   * ClassNotFoundException(String s, Throwable ex) constructor was
   * used to instantiate the object
   *
   * @serial
   * @since 1.2
   */
  private Throwable ex;

  /**
   * Constructs a <code>ClassNotFoundException</code> with no detail message.
   */
  public ClassNotFoundException() {
    super((Throwable) null);  // Disallow initCause
  }

  /**
   * Constructs a <code>ClassNotFoundException</code> with the
   * specified detail message.
   *
   * @param s the detail message.
   */
  public ClassNotFoundException(String s) {
    super(s, null);  //  Disallow initCause
  }

  /**
   * Constructs a <code>ClassNotFoundException</code> with the
   * specified detail message and optional exception that was
   * raised while loading the class.
   *
   * @param s the detail message
   * @param ex the exception that was raised while loading the class
   * @since 1.2
   */
  public ClassNotFoundException(String s, Throwable ex) {
    super(s, null);  //  Disallow initCause
    this.ex = ex;
  }

  /**
   * Returns the exception that was raised if an error occurred while
   * attempting to load the class. Otherwise, returns <tt>null</tt>.
   *
   * <p>This method predates the general-purpose exception chaining facility.
   * The {@link Throwable#getCause()} method is now the preferred means of
   * obtaining this information.
   *
   * @return the <code>Exception</code> that was raised while loading a class
   * @since 1.2
   */
  public Throwable getException() {
    return ex;
  }

  /**
   * Returns the cause of this exception (the exception that was raised
   * if an error occurred while attempting to load the class; otherwise
   * <tt>null</tt>).
   *
   * @return the cause of this exception.
   * @since 1.4
   */
  public Throwable getCause() {
    return ex;
  }
}
